Systems, devices and methods for distributing data with multi-tiered encoding

ABSTRACT

Systems, devices, methods, and computer readable media are provided for distributing data with multi-tiered encoding. For example, a system for transmission of data streams to endpoints is provided that includes: encoders, each encoder configured to encode a data stream according to at least one encoding parameter; virtual transmitters organized into groups based on at least one transmission characteristic; each group of virtual transmitters configured to receive encoded data from an associated one of the encoders; each virtual transmitter of the plurality of virtual transmitters configured to transmit the encoded data to an associated one of the plurality of endpoints; and at least one controller configured to monitor transmission characteristics of the plurality of virtual transmitters and to adjust membership of the virtual transmitters in the plurality of groups based on the monitored transmission characteristics. The system may be further configured for synchronization, uni/bi-directional communication, etc.

CROSS REFERENCE

This application is a non-provisional of, and claims all benefit to,including priority to, U.S. Application No. 62/145,363 filed Apr. 9,2015 and entitled “SYSTEMS DEVICES AND METHODS FOR DISTRIBUTING DATAWITH MULTI-TIERED ENCODING”, incorporated herein by reference.

FIELD

The disclosure relates generally to data communications, and moreparticularly to systems, devices, methods and computer program productsfor data communication to and from but not limited to video transmittersand receivers.

BACKGROUND

Transmission of live video or other data from one location to multipleendpoints is a common issue across a number of industries. Frombroadcast quality live shots that need to be transmitted to numeroustelevision stations across a wide geography to security or emergencyscene information that needs to be available to a variety of usersincluding first responders and control center staff, a cost effectiveand reliable manner in which to transfer this information may bedesirable.

Some of the receiver endpoints (e.g., a TV studio) may have variousstated requirements for incoming video quality and latency, or may havechallenges in receiving high quality, low latency video due toinadequate or inconsistent transmission networks.

SUMMARY

In an aspect, there is provided a system for transmission of datastreams to a plurality of endpoints, the system comprising: a pluralityof encoders, each encoder configured to encode a data stream accordingto at least one encoding parameter; a plurality of virtual transmittersorganized into a plurality of groups based on at least one transmissioncharacteristic; each group of virtual transmitters configured to receiveencoded data from an associated one of the encoders; each virtualtransmitter of the plurality of virtual transmitters configured totransmit the encoded data to an associated one of the plurality ofendpoints; and at least one controller configured to monitortransmission characteristics of the plurality of virtual transmittersand to adjust membership of the virtual transmitters in the plurality ofgroups based on the monitored transmission characteristics.

In another aspect, at least two of the groups correspond to rankedtiers, ranked according to the at least one transmission characteristic.

In another aspect, the at least one controller is configured to adjustthe membership of the virtual transmitters in the plurality of groups,the at least one controller being configured to: upon a determinationthat a group membership adjustment condition has been triggered,determine a new group for a target virtual transmitter that is currentlya member of a current group, the new group based on the monitoredtransmission characteristics; determine whether a current frame numberbeing processed by the current group matches a new frame number beingprocessed by the new group; generate and transmit a control signal to anencoder corresponding to the new group requesting provisioning of thetarget virtual transmitter as a member of the new group; request a keyframe from the encoder corresponding to the new group; and upon adetermination that the current frame number does not match the new framenumber, generate or transmit one or more control signals to synchronizethe target virtual transmitter to the encoder corresponding to the newgroup.

In another aspect, to synchronize the virtual transmitter when thecurrent frame number is greater than the new frame number, the at leastone controller is configured to: transmit a control signal to an encodercorresponding to the current group terminating membership of the targetvirtual transmitter and transmit a control signal to the virtualtransmitter to discard frames provided by the encoder corresponding tothe new group until frames provided by the encoder corresponding to thenew group reach the current frame number.

In another aspect, to synchronize the virtual transmitter when thecurrent frame number is less than the new frame number, the at least onecontroller is configured to: maintain membership of the target virtualtransmitter in both the current group and the new group and store theframes provided by the encoder corresponding to the new group in asorted queue until the frames provided by the encoder corresponding tocurrent group match the earliest frame provided by the encodercorresponding to the new group, upon which the at least one controlleris configured to transmit a control signal to the encoder correspondingto the current group terminating membership of the target virtualtransmitter and to transmit a control signal to the virtual transmitterto process the frames stored in the sorted queue.

In another aspect, each encoder of the plurality of encoders isconfigured to encode the data stream according to a lowest transmissioncharacteristic among the plurality of virtual transmitters that aremembers of the group corresponding to the encoder.

In another aspect, the at least one controller is configured to monitorload conditions, each load condition associated with an encoder of theplurality of encoders, and upon detecting load conditions greater than apredetermined load condition value, to provision a new encoder and acorresponding new group, and to adjust membership of the virtualtransmitters in the plurality of groups such that the virtualtransmitters are distributed substantially evenly amongst the pluralityof groups.

In another aspect, the system further includes a decoder configured todecode data received from a data source, and to provide the decoded datato each of the plurality of encoders.

In another aspect, the system further includes a plurality of decoders,each associated with at least one of plurality of encoders, each of thedecoders configured to decode data received from a data source, and toprovide the decoded data to the associated encoders.

In another aspect, the at least one transmission characteristiccomprises at least one of: a bitrate, a latency, an encoding error raterelative to individual encoding, a structural similarity metric, apicture similarity index, and a packet loss rate.

In another aspect, there is provided a computer-implemented method fortransmission of data streams to a plurality of endpoints, the methodcomprising: monitoring, by at least one controller, transmissioncharacteristics of a plurality of virtual transmitters; and adjustingmembership of the virtual transmitters in a plurality of groups based onthe monitored transmission characteristics; wherein a plurality ofencoders are each configured to encode a data stream according to atleast one encoding parameter, and the plurality of virtual transmittersare organized into the plurality of groups based on at least onemonitored transmission characteristic; wherein each group of virtualtransmitters is configured to receive encoded data from an associatedone of the encoders; and each virtual transmitter of the plurality ofvirtual transmitters is configured to transmit the encoded data to anassociated one of the plurality of endpoints.

In another aspect, at least two of the groups correspond to rankedtiers, ranked according to the at least one transmission characteristic.

In another aspect, adjusting the membership of the virtual transmittersin the plurality of groups, further includes: upon a determination thata group membership adjustment condition has been triggered, determininga new group for a target virtual transmitter that is currently a memberof a current group, the new group based on the monitored transmissioncharacteristics; determining whether a current frame number beingprocessed by the current group matches a new frame number beingprocessed by the new group; generating and transmitting a control signalto an encoder corresponding to the new group requesting provisioning ofthe target virtual transmitter as a member of the new group; requestinga key frame from the encoder corresponding to the new group; and upon adetermination that the current frame number does not match the new framenumber, generating or transmitting one or more control signals tosynchronize the target virtual transmitter to the encoder correspondingto the new group.

In another aspect, to synchronize the virtual transmitter when thecurrent frame number is greater than the new frame number, the methodfurther includes: transmitting a control signal to an encodercorresponding to the current group terminating membership of the targetvirtual transmitter and transmitting a control signal to the virtualtransmitter to discard frames provided by the encoder corresponding tothe new group until frames provided by the encoder corresponding to thenew group reach the current frame number.

In another aspect, to synchronize the virtual transmitter when thecurrent frame number is less than the new frame number, the methodfurther includes: maintaining membership of the target virtualtransmitter in both the current group and the new group; storing theframes provided by the encoder corresponding to the new group in asorted queue until the frames provided by the encoder corresponding tocurrent group match the earliest frame provided by the encodercorresponding to the new group; when the frames provided by the encodercorresponding to current group match the earliest frame provided by theencoder corresponding to the new group, transmitting a control signal tothe encoder corresponding to the current group terminating membership ofthe target virtual transmitter; and transmitting a control signal to thevirtual transmitter to process the frames stored in the sorted queue.

In another aspect, each encoder of the plurality of encoders isconfigured to encode the data stream according to a lowest transmissioncharacteristic among the plurality of virtual transmitters that aremembers of the group corresponding to the encoder.

In another aspect, the method further includes: monitoring loadconditions, each load condition associated with an encoder of theplurality of encoders; and upon detecting load conditions greater than apredetermined load condition value, provisioning a new encoder and acorresponding new group, and adjusting membership of the virtualtransmitters in the plurality of groups such that the virtualtransmitters are distributed substantially evenly amongst the pluralityof groups.

In another aspect, the method further includes: a decoder configured todecode data received from a data source, and to provide the decoded datato each of the plurality of encoders.

In another aspect, the method further includes: a plurality of decoders,each associated with at least one of plurality of encoders, each of thedecoders configured to decode data received from a data source, and toprovide the decoded data to the associated encoders.

In another aspect, the at least one transmission characteristiccomprises at least one of: a bitrate, a latency, an encoding error raterelative to individual encoding, a structural similarity metric, apicture similarity index, and a packet loss rate.

DESCRIPTION OF THE FIGURES

In the figures, embodiments are illustrated by way of example. It is tobe expressly understood that the description and figures are only forthe purpose of illustration and as an aid to understanding.

Embodiments will now be described, by way of example only, withreference to the attached figures, wherein in the figures:

FIG. 1 is an example schematic diagram of a system with one multi-pointdistribution (MPD) node, according to some embodiments.

FIGS. 2A and 2B are example before-and-after depictions of a virtualtransmitter moving between tiers in the system of FIG. 1, according tosome embodiments.

FIGS. 3A, 3B and 3C, are example schematic diagrams of a system withmultiple replicated MPD nodes, according to some embodiments.

FIG. 4A is an example schematic diagram of a system with multipletransmitters serviced by multiple MPD nodes, according to someembodiments.

FIG. 4B is an example schematic diagram of a system with multiplereplicated virtual transmitter blocks, according to some embodiments.

FIG. 5 is a sample workflow diagram illustrating a method forsynchronizing clocks, according to some embodiments.

FIG. 6 is a schematic of a computing device, according to someembodiments.

FIG. 7 is a workflow illustrative of a method for distributing data withmulti-tiered encoding, according to some embodiments.

FIG. 8 is a workflow illustrative of a method for adjusting a virtualtransmitter between two different tiers, according to some embodiments.

DETAILED DESCRIPTION

Embodiments of methods, systems, and apparatus suitable for use inimplementation are described through reference to the drawings. Thefollowing discussion provides many example embodiments of the inventivesubject matter.

Some solutions available on the market include individualized webstreams which do not allow for adequate quality or consistency and whichrequire excessive computation to generate the differing feeds, or costlydedicated data links between stations within a network or station groupwhich do not allow for easily customizable sets of customers to receivethe video or to interact with those producing it.

In some embodiments, a system is provided that facilitatescommunications between endpoints. There may be various types ofendpoints: there may be endpoints which can receive (a receiver);endpoints which can transmit (a transmitter); and/or endpoints that maybe capable of both transmitting and receiving, either separately orsimultaneously (a transceiver).

Communicated signals may represent various forms of information, and maybe analog and/or digital. The various forms of information may includemedia information (e.g., videos, audio, text, multimedia presentations,slide presentations, subtitles, 3D rendering information, andcombinations thereof), metadata information (e.g., bookmarks,annotations, comments, parity), header information, etc. These sourcesmay provide signals carrying information having various properties(e.g., analog, digital, compressed, scrambled, encrypted and/ordecoded). The signals from the sources may also be associated withvarious error correction, handshaking, redundancy and/or encodingtechniques that are used to improve information quality for signalstravelling through unreliable or noisy communication channels.

While the transmission sources may primarily be transmitting theaforementioned information signals, there may also be informationsignals going in the reverse direction, such as those required formonitoring and cueing in a broadcast environment (e.g., interruptiblefoldback or “IFB”).

The signals (both forward and reverse) may be transmitted throughvarious communications media and topologies, such as the Internet,point-to-point linkages, intranets, peer-to-peer networks, etc. Thesignals may also be transmitted using various communicationstechnologies, such as wired and/or wireless (e.g., microwave,Bluetooth™, cellular technologies).

Signals may include both frames carrying information, such as mediainformation, and key frames used to indicate starting and ending pointsof various elements of information (e.g., a transition, a transmission).The key frames may include various types of key frames, such asi-frames, instantaneous decoder refresh (IDR)-frames, etc. Where onetype of key frame is referred to in this specification, other types ofkey frames may also be utilized.

In some embodiments, the system may utilize one or more proxies fordistributing information. For example these proxies may be configured toreceive an encoded stream, and repeat it to one or more of other proxiesand/or one or more decoders. The use of one or more proxies may dependon the size and/or scale of a deployment—for example, the proxies mayhelp alleviate the load on cloud computing resources hosting multipledecoders, a source transmitter and/or on various communication linksbetween the transmitter and/or the decoders. There may be layers ofproxies (e.g., a master proxy feeding into one or more layers ofintermediate proxies). The layers of proxies, in some embodiments, areorganized as a hierarchy of proxies. The proxies may be controlled byone or more master controllers, or, for example, there may be one ormore intermediate proxies that are controlled by intermediatecontrollers.

The proxies may be configured to provide other functionality, such asrequesting missing information packets from the source, reconstructingmissing information packets from the source based on forward errorcorrection (FEC), transmitting the encoded information packets to eachof the downstream components next in the hierarchy of proxies and/ordecoders, handling retransmission of lost packets, forwarding key-frameon demand requests received from downstream components to the source,providing IFB capabilities (e.g., decoding IFB packets received fromdownstream components, mixing them into a single audio stream,re-encoding this stream, then sending it to the source), tracking loadreported by downstream components, handling requests from the dispatcher(e.g., starting a virtual transmission to an endpoint/receiver, bydelegating to a downstream computing resource in the hierarchy with theleast load, adding another downstream computing resource, removing anempty downstream computing resource and transitioning an active streamfrom a level in the hierarchy to another).

A virtual transmitter may provide or interface with a communication linkestablished between an endpoint and an encoder, the virtual transmitterbeing used for the transmission of information to/from the endpoint. Thevirtual transmitter may be uni-directional, or bi-directional, and theinformation may include content data, appended data (e.g., subtitles,logos, overlaid images), metadata, control data, signal data, errorcorrection data, among others. The virtual transmitter may be provided,for example through a physical antenna array, a wired linkage, acellular connection, a bonded connection, etc. The virtual transmittermay operate various channels and sub-channels, each having varioustransmission characteristics (e.g., throughput, latency, packet loss,encryption, protocol), among others. The virtual transmitter may beconfigured to communicate with one or more controllers, for example,communicating electronic signals representative of network transmissioncharacteristics, endpoint characteristics, requested information signalcharacteristics, load conditions, operating conditions, among others.

As an illustrative, non-limiting example, “virtual” vs. “physical” maybe considered from the point of view of a user of the system. Forexample, with a physical transmitter, the user owns a piece ofequipment—the user plugs a video source (e.g. camera) into thisequipment, assign it to a destination, and starts the transmission overany network connections attached to this equipment (e.g., cell modems,WiFi, ethernet, etc.).

For a virtual transmitter, the user may not see/own a particular pieceof hardware but rather, in some embodiments, the service may be run inthe cloud or using distributed resources, where the video source is notdirect (like a camera), but instead, is an indirect source (such as alive feed from a physical transmitter, or a file on disk (or othermedia)). Transmission occurs over network connections that exist to thecloud server (or distributed resources) on which the virtual transmitterruns on.

The virtual transmitter may send signals that are analog and/or digitalin nature, that may incorporate the usage of various signalcompression/encoding (e.g., multiplexing/simplex signals, duplexing,time division, frequency division, code division, modulation),redundancy (e.g., sending parity checks and/or cloned signals), and/orerror encoding/correction techniques (e.g., handshakes, echocancellation). These signals may be transmitted over the one or morecommunication links.

In some embodiments, the virtual transmitter is configured to receive orgenerate control commands, including, for example, coded instructionsets, machine-level instructions, object code, etc. These controlcommands may be sent to the controller or an encoder, or received fromthe controller or the encoder, such that the virtual transmitteroperating characteristics are modified. For example, the virtualtransmitter may be adapted for providing a link between the endpoint andthe encoder, and the virtual transmitter may be configured to establishlinkages, break linkages, with or two endpoints and encoders. Forexample, the virtual transmitter may receive a control instruction setrequesting the virtual transmitter to break a connection with a firstencoder in favour of a second encoder where the virtual transmitter ismoving from one encoding group (e.g., tier) to another.

The system may include one or more bonding components configured to bondcommunication links to form a bonded communication link. Communicationlinks may be bonded in manners similar to that described in U.S. Pat.No. 8,873,560 to Frusina and Horvath (hereinafter referred to as the'560 patent) or in U.S. Pat. No. 8,984,576 to Sze et al. (hereinafterreferred to as the '576 patent), the contents of both are herebyincorporated by reference. For example, the system may split datacommunication into multiple data streams transmitted in disassembledform over multiple communication links by way of multiple radiofrequency (RF) interfaces (e.g., modems). Such disassembly may include,for example, transmitting packets from one data source over multiple RFinterfaces, transmitting packets out of order, transmitting redundantpackets, re-transmitting missing packets, computing and transmittingforward error correction (FEC) data, etc. The system may also includeone or more complimentary de-bonding components configured to allow datacommunications over a bonded communication link to be re-assembled orotherwise reconstituted for use once transmitted through a bonded link.Such re-assembly may include, for example, re-ordering data packets,reassembling data packets, re-requesting missing data packets,re-computing missing packets based on FEC data, etc.

In some embodiments, the signals for transmission may beencoded/transcoded and/or otherwise transformed, for example, thesignals may be modulated based on a specific encoding scheme (e.g.,using various codecs, amplitude modulation, frequency modulation,code-division multiple access schemes, frequency division multipleaccess schemes, time division multiple access schemes, quadrature phaseshift keying schemes), encrypted (e.g., using public/private key pairs),scrambled, filtered, digitized, enhanced, degraded, compressed, etc.Additional information (e.g., logos, advertisements, timestamps,geocoding, audio or graphical overlays) may be appended to or mergedinto the signals for various purposes.

In a first embodiment, a system is provided for receiving signals fromthe first set of one or more endpoints, grouping the second set of oneor more endpoints into one or more groups, and performing encoding ofthe received signals, wherein the encoding of the data is based on atleast one of the characteristics of the group members. One or moreencoders may be provisioned, at least one encoder for each of thegroups, the encoders configured to encode the signal based on a minimumcharacteristic of the endpoints comprising the group.

According to some embodiments, a potential advantage of grouping theendpoints for encoding may be the reduction of the number of encodersand/or the processing required to encode the signals for use by theendpoints.

There may be various characteristics that may be used in determininggroupings for endpoints, these characteristics including, for example,average bit rate, minimum bit rate, affiliated entities (e.g., theseendpoints are to be branded with similar logos), geography, language(e.g., these endpoints require Spanish subtitles), accessibility (e.g.,these endpoints require closed captioning), network componentconsiderations (e.g., these endpoints are behind a firewall and/or theseendpoints can only be reached using a specific port), latency,connection reliability, connection uptime, nature of connections betweentransmitters, encoders and endpoints (e.g., some linked via fibre,others via satellite), audio or video transmission format (e.g. adaptiveor fixed bitrate, different encoding types), different audio components(e.g., Stereo vs. 5.1 Surround Sound), desired language of audio overlay(e.g., English or Spanish commentary), time requirements (e.g., theseendpoints only broadcast from 6:30 PM-8:30 PM), media to be broadcast(e.g., these endpoints are audio-only feeds), security level (e.g.,these endpoints are restricted from receiving certain metadataassociated with the transmission or these endpoints may not receivevideo from certain locations, or these endpoints must be sent onlyencrypted transmissions), payment level (e.g. these endpoints arelimited to certain bandwidth or time slices based on what they havepurchased), etc.

The groupings may be segregated, ranked, and/prioritized. For example,the groups may be tiered or set out in tiers, (e.g., tier one is the setof endpoints having a bit rate of 10-50 Mbps, tier two is the set ofendpoints having a bit rate of 3-10 Mbps, tier 3 is the set of endpointshaving a bit rate of 0-3 Mbps). The order of the tiers may be important;in some embodiments of the system, preference may be given to a highertier over a lower tier. Such preferences may change over time inresponse to various factors (e.g. a tier may take priority when thegroup of endpoints in that tier are scheduled for a prime-time newsbroadcast, but drop in priority outside of that time period). Groupingsmay also be across multiple dimensions, for example, an endpoint may bea member of one or more groups.

As an illustrative, non-limiting example, consider a scenario wherethere are 5 virtual transmitters, each currently sending at thefollowing bitrates: VTx1: 1.5 Mbps, VTx2: 2.0 Mbps, VTx3: 3.5 Mbps,VTx4: 6.0 Mbps, and VTx5: 9.5 Mbps.

Without tiers, there would have to be sufficient computationalprocessing required to re-encode the video at those 5 distinct bitrates.With tiers, the transmitters would be “binned” into groups—e.g., Tier1:0-2.5 Mbps, Tier2: 2.5-5.0 Mbps, and Tier3: 5.0-10.0 Mbps. Tier1 wouldcontain: VTx1, VTx2. Tier2 would contain: VTx3. Tier3 would contain:VTx4, VTx5. With tiers, computational processing is used to re-encodethe video at only 3 distinct bitrates. Tiers may be, for example,specific groupings, and may be ranked, in some embodiments, or notranked, in other embodiments. For example, tiers/groups may beestablished not just by speed, but by other factors, such as therequirement for uni/bidirectional content, error encoding, logos,subtitles, etc. Each of these factors may have computational processingimpacts on the encoders, and may need to be taken into consideration inensuring that a membership of the groups is established (or adjusted) tomaintain a greater level of efficiency. For example, determining themembership of the groups may be performed at one time, periodically orcontinuously by the encoders and/or controller. While the base case isto group the virtual transmitters to reduce computational processingrequired relative to each virtual transmitter being encoded separately,in some embodiments, membership is derived taking into consideration thequality of service delivered to each virtual transmitter (e.g., how goodof a ‘fit’ a particular group is, the aggregate amount of encodingresources required for encoding signals to the virtual transmitters, thetotal amount of encoding resources available).

The membership of the groups may also be dynamic. For example, theendpoints comprising a group may adapt over time for various reasons,such as changing network conditions, changing demand requirements,changing resource availability, scheduling, payment for on-demand accessto a feed, etc.

In some embodiments, the groupings may be provided (e.g., from anexternal system or from the endpoints themselves). In some embodiments,the groupings may be determined by the system, using information such assensed real-time information (e.g., using a network monitoringcomponent), historical information, predicted information, endpointcharacteristic information (such as but not limited to location, paymentstatus, security clearance level), etc.

In some embodiments, membership of endpoints in various groups may bedetermined by the system, and the system may move one or more endpointsfrom one group to another group (e.g., the requirements of the endpointindicate that the endpoint would be more efficiently served if it were amember of another group). In some embodiments, membership of endpointsin various groups may be determined by the endpoint, which, for example,may request a transfer from one group to another group.

In some embodiments, the system is configured for the determination ofvarious aspects related to the grouping of endpoints, including thecriteria used to determine membership into groups, the rankingand/prioritization of groups, the number of groups to be provisioned,the number of endpoints that should fall within a group, etc. Thedetermination of aspects related to the grouping of endpoints may beconducted, for example, through the use of an optimization algorithmthat optimizes various factors, such as delivery efficiency, overallcost, processing cycles, efficiency of encoding, efficiency of decoding,service levels, and/or various combinations of factors. For example,various factors may have weight co-efficients assigned to them such thata weighted aggregate of factors may be used in determining how groupingsshould be allocated. Grouping may be determined through the use ofvarious rules, conditions, rules, triggers, etc.

The criteria may include the total amount of resources available forencoding. For example, computing resources may be finite and sharedamongst a larger pool of resources where some resources are used forother functions (e.g., news-casting, other signal transmissions) and theresources available may also be dynamic. The system may be configuredfor load balancing or predicting computational resources availability,and the groupings may be established to ensure that encoding activitiesare a good fit for the amount of resources available (or predicted to beavailable). For example, if a period of reduced resources is expected,the system may proactively group the virtual transmitters (e.g.,adjusting membership to reduce the number of groups) such that encodingload is reduced. Conversely, if a period of available resources isexpected, the system may proactively group the virtual transmitters(e.g., adjusting membership) such that encoding load is increased (e.g.,more granular groups) and the virtual transmitters may receive a greaterquality of service.

In some embodiments, other components may be utilized, such as decodersfor decoding encoded source signals, virtual transmitters (that may beassociated with one or more endpoints for the transmission of signal tothese one or more endpoints), controllers (e.g., for load balancing),etc.

In some embodiments, the methods and systems described in thisspecification may be used, for example, in conjunction with amulti-viewer system as described in U.S. patent application Ser. No.14/329,112 (published as US20150020135A1 to Frusina, hereinafterreferred to as the '112 application), the contents of which are herebyincorporated by reference in its entirety.

In conjunction with this multi-viewer system, there may be variousstreams provided by transmitters, for delivery to endpoints/receivers(e.g., for viewing at and control by an endpoint/receiver). Thesestreams may include various audio/video/metadata streams, previewstreams, streams at various bitrates, etc. Streams from multipletransmitters may be transmitted in parallel to an endpoint/receiver forsimultaneous viewing at the endpoint/receiver. In manners disclosed inthe '112 application, a low bit rate/low frame rate preview stream maybe provided to endpoints/receivers for preview purposes. Further, inmanners disclosed in the '112 application, there may be provided aninterface for selection and assignment of one or more streams fortransmission to each endpoint/receiver. Some streams may be processed(e.g., decoded, encoded, transmitted, and operated on) in mannersdisclosed herein.

FIG. 1 is an example schematic diagram 100 of a system with onemulti-point distribution (MPD) node 120, according to some embodiments.

As depicted, the MPD node 120 includes a decoder 104, an MPD controller106, a plurality of tier controllers 108 a . . . 108 n, a plurality ofre-encoders 110 a . . . 110 n, and a plurality of virtual transmitters112 a . . . 112 n. The MPD node 120 is interconnected with a sourcetransmitter 102, one or more receiver endpoints 114 a . . . 114 n, and acontrol portal 150.

Tier controllers 108 a . . . 108 n, re-encoders 110 a . . . 110 n, andvirtual transmitters 112 a . . . 112 n are organized into group. Eachgroup include one tier controller 108, one re-encoder 110, and a subsetof the virtual transmitters 112 a . . . 112 n. Each of these subsets ofvirtual transmitters 112 a . . . 112 n may be referred to as a virtualtransmitter block 130. The number of re-encoders 110 a . . . 110 n maybe selected to optimize one or more variables tracked by the system. Forexample, the system may also be adapted to optimize the one or morevariables and in some embodiments, may provision or de-provisionre-encoders as required based on monitored supply, demand, and/or loadconditions.

Decoder 104 decodes data received from transmitter 102 and provides thedecoded data to the re-encoders 110 a . . . 110 n, each of whichre-encodes the data under control of an associated tier controller 108.In some embodiments, there may be one or more tier re-encoders 110 a . .. 110 n that can sometimes operate as the “null” re-encoder. In thesesituations, decoder 104 may also operate as a “null” decoder, meaningthe video/audio/metadata is passed through in its original form fromtransmitter 102 to one or more endpoints 114 a . . . 114 n.

Each of the re-encoders 110 a . . . 110 n provides re-encoded data to anassociated virtual transmitter block 130 for transmission by the virtualtransmitters 112 a . . . 112 n in that block 130. Each of the virtualtransmitters 112 a . . . 112 n transmits re-encoded data to an assignedendpoint 114 a . . . 114 n.

In some embodiments, a transmitter 102 may be associated with anendpoint 114 by first assigning the transmitter 102 to the decoder 104and then assigning a virtual transmitter 112 to the endpoint. In someembodiments, the assignment of a virtual transmitter 112 to an endpointmay be done in a manner that is transparent to an end user (e.g., at theendpoint).

For example, the end user may simply select a source transmitter 102(e.g., by drag-and-drop setup of a source transmitter 102 to an endpoint114). Thereafter, a virtual transmitter 112 is automatically selectedfor and paired with the endpoint 114, in some embodiments, through adouble assignment whereby the transmitter 102 is assigned to the decoder104, a virtual transmitter 112 is deployed or created on-the-fly and theoutput of the virtual transmitter 112 is assigned to the endpoint 114where the source transmitter 102 was dragged.

In the example of FIG. 1, the groups of virtual transmitters 112 servedby a common re-encoder 110 and controller 108 may be referred to astiers.

Some of the controllers provided are configured to operate at the levelof a tier, and may be referred to as tier controllers 108 a . . . 108 n.A MPD controller 106 may be provided in the MPD node 120 to manage theoperations of the node 120. For example, an MPD controller 106 may beconfigured to define tiers, dynamically spin-up cloud compute resourcesas required, manage tiers (e.g. may override a tier controller 108 tomanage number of virtual transmitters in a tier), manage the transfer ofvirtual transmitters 112 between tiers, handle interactions with a proxy(further described with reference to FIG. 3A-3C) and/or decoder 104, andwith the transmitter 102 via the proxy, among others.

In some embodiments, a cloud server may also be associated with a tier,facilitating transmission to endpoints via a content distributionnetwork (CDN) or similar that accepts the real time messaging protocol(RTMP), HTTP live streaming (HLS) or similar real time streamingprotocols.

In some embodiments, the system is configured for handling errorcorrection data, which may be separate from data content. For example,of the link between 112 a and 114 a might be perfect, so zero errorcorrection would be required. Conversely, the link between 112 b and 114b might be suffering from 5% loss, requiring 5% error correction. Inboth cases above the content is the same (as generated by the Tier1re-encoder (110 a), but the error correction data is different. Errorcorrection data may be transmitted across the same or differentchannels. Where error correction data is transmitted on differentchannels of a communication link, in some embodiments, a faster channel(e.g., lower latency) is selected such that error correction is receivedfaster such that corrupt (e.g., fails parity check)/missing (e.g., didnot arrive on time)/malformed (e.g., header corrupted) data can bere-requested and actioned responsively (e.g., quickly).

The MPD controller 106 may interact with other components through, forexample, sending control signals, the control signals indicating, forexample, information on needed changes to tier parameters, informationon virtual transmitters 112 that need to move into a new tier, andconfirmations when a move is complete; to decoders or proxies, feedbackon tiers (e.g. stop transmitting/decoding, as there is no longer anydemand for the stream for a particular location). The MPD controller 106may also be configured to send signals to receivers, for example, IFBcontrol information indicating which receiver and/or component is incontrol of sending and receiving audio as well as status information(bandwidth usage, lost frames and other key performance parameters).

A control portal 150 may be provided to enable configuration and statusmonitoring of the MPD controller 106 (e.g., by way of MPD node controlinput 125). This may be implemented using a variety of approachesincluding, but not limited to a web application, a mobile application ora custom software application. The control portal may also be configuredwith and/or distributed with access and permissions controlled by userroles and log-on credentials.

In some embodiments, a separate IFB controller is provided that isconfigured to allow for the switching and management of IFB coming froma receiver endpoint 114 to the transmitter 102 as well as provide forswitching and management of additional audio sources (e.g., a sessioninitiation protocol (SIP) conference/dial-in service) that can beoptionally used for IFB. The IFB controller can optionally be managed bythe MPD controller 106. Configuration and status information for the IFBcontroller is handled by the control portal 150

Using the control portal 150, the MPD controller 106 may be configuredby a user to determine the number of tiers required based on variouscriteria, such as cost, computing power needed, data bandwidth requiredand/or utilized and/or statistical analysis of historical transmissionand reception characteristics for given devices or geographies. Tiersmay be provided for various encoding requirements (e.g., bitrate ranges,bitrate consistency, encoding formats, information to be appended oroverlaid to an incoming information flow).

There may be limits on the size of each tier (e.g., the number oftransmitters) with both a minimum and a maximum, and the MPD controller106 may be configured to manage the process of re-allocating virtualtransmitters 112 between tiers, and/or dynamically changing thecharacteristics of tiers (e.g., additional resources have becomeavailable, increase the maximum number of virtual transmitters in atier, data bandwidth allocation close to being exceed or alreadyexceeded).

In some embodiments, the number of tiers may change dynamically. Forexample, tiers may be added to accommodate new transmitters (possibly indifferent locales with different decoder requirements) or collapsed toreduce computing and/or bandwidth cost. The addition or removal of tiersmay be implemented based on monitored behaviour of the virtualtransmitters, or other network condition characteristics usingmanagement criteria that are set via the control portal 150 or othersystem policy. The tier boundaries (e.g., 3-5 Mbps), may also change(e.g., to 3-6 Mbps)—for example, if the costs were fixed (e.g., limitingnumber of encoders), tier boundaries may be configured to fluctuate tobest allow the virtual transmitters (or certain priority virtualtransmitters/receivers within a pool) to operate closer to a desiredlevel rather than move a virtual transmitter down to a tier withconsiderably lower performance. Tiers may also be de-provisioned and(re)provisioned to help manage costs. For example, where there arelimited cloud computing resources and there is a desire to manage (e.g.,maximize) the utilization of the cloud compute resources and/or datausage. Tiers may also be de-provisioned if the tier is idle for apre-determined period of time, etc.

Tier controllers 108 a . . . 108 n may be configured to maintain and/ortrack the status of virtual transmitters 112 a . . . 112 n, and todynamically, actively and/or passively adapt tier re-encoder 110 a . . .110 n settings (e.g., based on an optimization rule), making variousrecommendations to a MPD controller 106 in relation to the movementand/or allocation of virtual transmitters as between tiers. For example,the tier controllers 108 a . . . 108 n may transmit signals indicatingthat a virtual transmitter needs to be assigned to a new tier given itsperformance (e.g., too slow, too fast, too unreliable), and may transmita signal to the MPD controller 106 indicating that the virtualtransmitter should be moved from one tier to another.

In this example, the source transmitter 102 (T_(x)) is a video sourcetransmitter that supplies live video to an indeterminate number ofreceiver endpoints 114 a . . . 114 n (R₁ to R_(N)). This video may betransferred by various means, including but not limited to, transferover a bonded communication link as described in the '560 patent or the'576 patent.

The source transmitter 102 may be transmitting an encoded signal thatrequires decoding. The source transmitter 102 may communicateinformation or otherwise interact with a decoder 104.

The decoder 104 may be configured for the following functionality:receiving the encoded information packets from an upstream component(e.g., a source transmitter 102, a master Proxy, or an IntermediateProxy), requesting missing information packets from the upstream,reconstructing missing information packets from the upstream componentbased on error correction (e.g., forward error correction techniques),decoding the information packets to raw frames, adjusting timestamps andother metadata on the raw frames as necessary, and/or passing the rawframes on to the re-encoder tiers.

For example, the decoder 104 may assemble and decode the incominginformation (e.g., audio, text, video, metadata) packets, and thenforward the information (e.g., in the form of a data stream) to one ormore re-encoder tiers, as determined by the MPD controller 106, whichmonitors the one or more tier controllers 108 a . . . 108 n.

If decoder 104 is the “null” decoder, it may omit any of theaforementioned operations before forwarding the data on to there-encoder tiers.

There may be one or more re-encoder tiers that may be provisioned by theMPD controller 106, the re-encoder tiers being associated with separatetiers that are configured for encoding signals and providing an outputinformation stream that is encoded based on characteristics associatedwith the tier (e.g., to a particular bitrate, having a particular logo,adding subtitles or other overlays).

For example, a re-encoder tier may include or be otherwise associatedwith a number of virtual transmitters 112 a . . . 112 n that areassigned to the tier (i.e., a virtual transmitter block 130), beconfigured to receive raw frames from decoder 104, re-encode themaccording to various rules (e.g., the worst bitrate and most aggressiveglass-to-glass latency (GTG) (e.g., the GTG may affect the encoderconfiguration) reported by all of the virtual transmitters 112 a . . .112 n assigned to its corresponding tier, deliver the encoded frames tothe virtual transmitters and/or request the tier controller 108co-ordinate movement of a virtual transmitter 112 currently in this tierto another one (e.g., the virtual transmitter performance may indicatethat the virtual transmitter should be associated with a different tier,such as a higher tier or a lower tier). For ease of management andsetup, all receiver endpoints within a tier may be initially set to thesame GTG and offsets from this GTG may be applied to an individualtransmitter via the receiver endpoint settings or the control portal 150as required to maintain acceptable video quality within a reasonablerange of GTG adjustment.

Each tier controller 108 may be configured to manage interactions withone or more receiver endpoints 114, and creates and associates acorresponding virtual transmitter 112. The tier controllers 108 a . . .108 n may include and/or otherwise be associated with one or more tierre-encoders 110 a . . . 110 n, which may be configured for variousencoding and/or other conversion processes in relation to the received(and, in some embodiments, decoded) information received from the sourcetransmitter 102.

Interactions between various receiver endpoints 114 and the virtualtransmitters 112 a . . . 112 n may be governed, for example, usingvarious methods and systems described in U.S. Pat. No. 8,873,560 andU.S. Pat. No. 8,984,576, which are hereby incorporated by reference intheir entirety. For example, a network communication performance profilemay be used to split information into multiple data streams to improvetransmission of information between devices, and/or a buffer managementand transport controller may be utilized to facilitate consistent datareception.

Functionality provided by the tier controller 108 may include forwardingkey-frame on demand requests received from the tiers to an upstreamcomponent (e.g., the source transmitter 102 or the tier re-encoder 110),decoding IFB packets received from the virtual transmitters, mixing theminto a single audio stream, re-encoding the audio stream, and/orswitching the audio stream provided to the upstream component (e.g., thesource transmitter 102). The tier controller 108 may also track load andreport it to various other components (e.g., the MPD controller 106),and/or co-ordinate the movement of a virtual transmitter 112 from onetier to another, and/or handle various requests from the upstreamcomponents (e.g., starting a virtual transmission to anendpoint/receiver, by delegating to the downstream branch with the leastload, adding another downstream branch, removing an empty downstreambranch and transitioning an active stream from level in the hierarchy toanother). As outlined above, IFB may also be handled using a separateIFB controller. In this case, the decoding, mixing, re-encoding,switching and management of IFB signals would be handled by the IFBcontroller instead of the tier controller.

The tier controller 108 may also be configured to manage and/orotherwise control various aspects of the tier re-encoder 110, whichre-encodes the stream sent from the decoder 104 for one or more virtualtransmitters 112, within the encoding parameters dictated by the tierboundaries, for example at a specific bit rate range (e.g. 5-10 Mbps).In some embodiments, the tier boundaries, and the number of tiers may bedetermined by the system using various optimization algorithms andtechniques. The use of such techniques may be used to increase serviceefficiency, reduce cost, etc.

In some embodiments, configuration of group/tier properties (e.g.,bitrates) may be statically chosen at system start-up, while in otherembodiments, a more intelligent (e.g., dynamic,continuously/periodically adjusted) determination may be utilizedwherein membership of tiers is automatically/semi-automatically adjusted(e.g., utilizing an error minimization control technique, such as afeedback loop, a PI controller, a P controller, a PID controller, amongothers). Adjustments may be made based on tracked control parameters, adiversity of control parameters, weighted control parameters, etc.

As an example, where there are constraint is provided wherein a maximumof 3 tiers are supported on a particular machine, the following 5 VTxesare supported: VTx1: 1.5 Mbps, VTx2: 2.0 Mbps, VTx3: 3.5 Mbps, VTx4: 6.0Mbps, and VTx5: 9.5 Mbps. Choosing 3 tiers may be determined, forexample, by choosing 2 of the VTxes in the list as the Tier boundaries.Iterative approaches may be used to determine how the groups and thetier boundaries are selected. For example, as a first “guess”, assumethat the controller chooses VTx1 as the first boundary, and VTx2 as thesecond. In this scenario, the three tiers are: Tier1: 0-1.5 Mbps, Tier2:1.5-2.0 Mbps, and Tier3: 2.0-max Mbps. The overall system “error” inthis case would be: =(Tier1Error)+(Tier2Error)+(Tier3Error)=(1.5−1.5)+(2.0−2.0)+(3.5−2.0+6.0−2.0+9.5−2.0)=(0)+(0)+(1.5+4.0+7.5)=13.0Mbps.

A possible method would be to exhaustively try all possible “guesses”,and select the combination that results in the lowest overall error.Where there are a large number of possible permutations and/orcombinations of tiers and tier values, various simulations may beutilized (e.g., exhaustive, non-exhaustive, deterministic, orprobabilistic approaches) to determine the potential efficiency gainsassociated with each permutation/combination, along with theirassociated trade-offs (e.g., errors, adequacy of encoding parameters). Alibrary of parameters may be stored along with performance (e.g.,efficiency) metrics and trade-off (e.g., error) metrics. The library maybe computed ahead of time or periodically developed such that the systemmay have available a set of pre-analyzed options for grouping control,adaptable for particular situations and scenarios, including predictedfuture situations and scenarios (e.g., adjustment of membership fromgroup to group or provisioning/de-provisioning of encoders may take timeto perform and may have to be initiated earlier).

In some embodiments, the adjustment criteria are established tominimizing overall bitrate error and/or to maximizing overall structuralsimilarity (SSIM). For example, the system may be configured determiningmetrics for re-encoding a video frame at the custom bitrate requested byeach VTx (essentially simulating the scenario where the system hasenough computational resources to run a tier for each one), for example,determining the SSIM for each of these encoded frames, and calculatingthe SSIM “error” between these theoretical frame versus the actual videoframe that was transmitted by the VTx. In some embodiments, a picturesimilarity index (PSIM) metric is tracked and controlled for.

If tier re-encoder 110 is the “null” re-encoder, the tier controller 108may omit any of the aforementioned operations before forwarding the dataon to the virtual transmitters 112.

Each virtual transmitter 112 may be paired with a corresponding receiverendpoint 114. The virtual transmitter 112 manages the transmission ofthe newly re-encoded video stream to at least one receiver endpoint 114,and may be configured to report various transmission characteristics,for example, latency, packet loss, trace-route and/or throughput, backto the tier controller. The virtual transmitter 112 may, in someembodiments, be a cloud based representation of a physical transmitterin the way that it interacts with the receiver (e.g., the receiverinteracts with the virtual transmitter the same way it would if it wasthe physical transmitter; the receiver may not be aware that the virtualtransmitter is an abstraction that allows the physical transmitter toefficiently transmit to multiple endpoints). The virtual transmitter 112may be configured to transfer data to an endpoint 114 by various means,including but not limited to, transfer over a bonded communication linkas described in the '560 patent or the '576 patent.

The virtual transmitter 112 may also receive and pass-through controldata, IFB, or other content from the receiver endpoint 114, which may berelayed to the transmitter 102. For example, such control data and/orother content may be used for monitoring and cueing purposes, etc.

In some embodiments, the system may be configured to interoperate with amulti-viewer system as described in the '112 application. In suchembodiments, each virtual transmitter 112 may be a transmitterselectable by a multi-viewer system (e.g., for shot selection purposes,or remote control purposes, etc.). As such, each virtual transmitter 112may be configured for the exchange of control signals with amulti-viewer system, in various manners as described in the '112application.

Low bitrate and/or low frame rate previews may be provided by thetransmitter 112 as described in the '112 application and these previewspresented to users by way of the control portal 150 for assignment,selection, etc., of video streams for distribution to one or moreendpoints.

In some embodiments, the re-encoder 110 in each tier adjusts adaptivelyto suit the lowest performing receiver in the set, within a pre-setand/or adaptive range, where the range might include parameters such asbut not limited to bitrate or latency, or of combinations of suchparameters. For example, the characteristics of the encoding may bedetermined using a cost-optimizer in relation to the number of receivers114, characteristics of receivers 114, the processing cost (e.g., incycles) of various encoding processes, the monetary cost associated withvarious encoding processes, etc. Other embodiments (e.g., using acombination of the two lowest performing receivers in the set or usingderived statistics from selected receivers in the set) are alsopossible.

The components at various levels (e.g., virtual transmitters 112 in ablock 130, a re-encoder 110, a tier controller 108, an MPD controller106) may be configured to report usage and/or issues to various othercomponents and also to the control portal 150. For example, if virtualtransmitters 112 a . . . 112 n are statically assigned with endpoints,usage tracking may be provided at a virtual transmitter level. Asanother example, if virtual transmitters 112 a . . . 112 n aredynamically assigned to endpoints, usage tracking may be provided atanother level in the hierarchy.

In some embodiments, the system is configured to establish the tiersusing historical data (e.g., from a standing start) and initial feedbackto configure the virtual transmitters 112 a . . . 112 n. For example,this data may be used to determine the number of tiers, the segregationbetween tiers, etc.

In some embodiments, the system may add and remove virtual transmitters112 throughout the transmission, for example, as receiver endpoints 114select to receive the video stream or stop receiving the stream.

In some embodiments, the system may be configured to provide IFB fromthe receive endpoints and IFB switching and/or mixing. In someembodiments, the use of switched IFB would allow different endpoints 114(e.g. news anchors at one of the stations receiving the transmission) tointeract with the transmitters 102 (e.g. a field reporter) through oneor more connections between the transmitter 102 and the system that aremanaged by the MPD controller 106 or a separate IFB controller using thecontrol portal 150.

The system may be implemented using discrete devices, or may beimplemented using a distributed networking (e.g., cloud computing)topology. Where a distributed networking implementation is utilized,various resources and components can be virtual or physical. Theresources can be provisioned and/or de-provisioned (e.g., spun up, spundown) and may be provided in various geographies (e.g., provisioning aserver in the Eastern portion of the United States) and with variousassociated connections. In some embodiments, the MPD controller 106and/or tier controllers 108 a . . . 108 n may be configured to requestthe provisioning and/or de-provisioning of resources possibly usinginformation and parameters provided by the control portal 150. Forexample, resource allocation may be determined through reports ofaggregate load from the MPD controller 106, and after the additionalresource is available, the MPD controller 106 could be configured tocoordinate adding the additional resource to a hierarchy of components.

In some embodiments, the endpoint receiver may schedule a time frame inwhich to request the IFB control channel to the transmitter using thecontrol portal 150. In some embodiments, the IFB channel would beselected on a first-come, first-serve basis. In some embodiments, thecontrol of the IFB channel may be determined at least in part by anoutside agent (e.g., the head office of the network providing thetransmission) acting through an interface with the MPD controller 106via the control portal 150.

Where there may be different components that may be separated bydistance (e.g., electrically or physically), communications andcoordination may require synchronization (e.g., of clocks, timers) asthere may be differences in latency, tolerances, variability, etc.

The synchronization may be conducted in various manners, such as at eachstage of transmission, for each packet, etc. In some embodiments, clocksynchronization between two components may be performed as described inU.S. Pat. No. 9,042,444 to Frusina et al., the contents of which areincorporated by reference. In some embodiments, the system may beconfigured to maintain latency and clock synchronization betweenmultiple stages of transmission (including decoding, re-encoding, andvarious steps of transmission) through the cloud.

In this sample scenario, the decoder 104, tier controller 108 andvirtual transmitter 112 reside on the same computing resource. In a morecomplex scenario, the decoder 104 and/or other components may be onseparate computing resources.

A clock synchronization process may need to be conducted between stagesif the deployment is running on different computing resources (physicalor virtual). FIG. 5 is a sample workflow diagram 500 illustrating amethod for synchronizing clocks, according to some embodiments.

According to some embodiments, in a typical deployment, the followingstages may be conducted on different computing resources:

-   -   (Tx) transmitter    -   (Px) proxy    -   (MPD) decoder, tier controller, virtual transmitter        (corresponding to an MPD node 120)    -   (Rx) receiver

Between each of these computing resources, a clock/time synchronizationprocess may be utilized, for example, periodically measuring thedistance between the two clocks, which is used to calculate the velocitybetween the clocks, and used to estimate the distance at a given pointin time. Given this set of distance estimates:

-   -   d(Tx-to-Px)    -   d(Px-to-MPD)    -   d(MPD-to-Rx)

An example is provided relating to a single media (e.g., video) frame asit is transferred through the system. At 502, the system firstperiodically determines estimated distances between clocks (e.g.,d(Tx,Px), d(Px,MPD), d(MPD,Rx) and makes values available to components.

1. At 504, a raw video frame captured by transmitter, and stamped withthe current capture time, t, as measured by the transmitter's clock;

2. At 506, the raw video frame is encoded, then transmitted to theproxy;

3. At 508, the proxy adjusts the timestamp on the video frame to:t+d(Tx-to-Px);

4. At 510, the proxy transmits the video frame to the MPD;

5. At 512, the MPD adjusts the timestamp on the video frame to:t+d(Tx-to-Px)+d(Px-to-MPD);

6. At 514, the MPD decodes the video frame, hands it off to the tiercontrollers 108 a . . . 108 n, which re-encode and hand it off to thevirtual transmitters;

7. At 516, virtual transmitters send the frame to thereceiver/endpoints;

8. At 518, the receiver adjusts the timestamp on the video frame fromto: t+d(Tx-to-Px)+d(Px-to-MPD)+d(MPD-to-Rx); and

9. At 520, the timestamp is now relative to the receiver/endpoint clock,allowing it to make a potentially more accurate decision of when to playit back with respect to the user's selected latency (e.g., glass toglass (GTG) latency).

In some embodiments, the re-encoding tiers may be formed across multipleaxes, to cover parameters such as but not limited to latency, quality,and consistency. Each axis may correspond to one parameter.

In some embodiments, the re-encoding tiers may be chosen and/oroptimized to minimize cost of transmission, cost of encoding, or otherfactors, and/or to maximize picture quality. The optimization of there-encoding tiers may, for example, be based upon data usageconstraints.

In some embodiments, a special “emergency” tier with lower bitrate maybe used for poorly performing virtual transmitters, to allow for aminimal transmission to be attempted while performance characteristicsare measured and evaluated. This information, for example, may be usedfor troubleshooting or for determining correct placement of the virtualtransmitter.

In some embodiments, metadata may be included in the stream and bepassed on to the various endpoints depending on a set of rules. Themetadata may provide various elements of information, such as timestamps, geocoding, source and ownership of data within the stream,relationship information (e.g., relationship between the originator ofthe transmission and the recipient), headers etc., and in someembodiments, the metadata may also be utilized in the determination ofgroupings, encoding and/or connection monitoring.

In some embodiments, the re-encoding groupings (e.g., tiers) may bedetermined and/or selected based on one or more overlays to be applied(e.g., automatically) to the re-encoded picture, such as but not limitedto a particular network's logo. Other information may be applied, suchas subtitles, markings, overlays, alternative audio tracks, closedcaptioning etc. In these embodiments new re-encoding groupings may bespun-up or spun-down as required to meet demands for new or eliminationof unused information. For example, in one embodiment certain groupingsspun-up for station or network markings may only exist at certainintervals (e.g. every 10 minutes a grouping is created to display aparticular overlay for 10 seconds, and then be spun-down until the nextinterval with the endpoints in the grouping dispersed to other tiersbased on other criteria.

FIGS. 2A and 2B are graphical representations which illustrate a samplebefore and after depiction of a virtual transmitter moving betweentiers, according to some embodiments.

As indicated in FIGS. 2A and 2B, there may be various scenarios where anendpoint, associated virtual transmitter and/or other device may bemoved from one group to another group. In this example, the groups arerepresented as different tiers, each tier corresponding to successivelyincreased bitrates (e.g., as indicated in FIG. 2A, there are two exampletiers, Tier 1 (5-10 Mbps), and Tier 2 (3-5 Mbps)).

FIG. 2A is a graphical representation of a schematic diagram 200A beforethe movement of a virtual transmitter between tiers, according to someembodiments.

Referring now to Tier 1, initially both virtual transmitters aretransmitting to corresponding receivers within the bitrate rangesspecified for Tier 1. In particular, Virtual Transmitter 1 istransmitting to Receiver 1 at 8 Mbps and Virtual Transmitter 2 istransmitting to Receiver 2 at 6 Mbps. For these transmission rates, Tier1 Controller controls the Tier 1 Re-encoder to encode video data at therate of the lowest-performing Virtual Transmitter in the tier, namely,at 6 Mbps to accommodate Virtual Transmitter 2.

Referring now to Tier 2, both virtual transmitters are transmitting tocorresponding receivers within the bitrate ranges specified for Tier 2.In particular, Virtual Transmitter 3 is transmitting to Receiver 3 at4.5 Mbps and Virtual Transmitter 4 is transmitting to Receiver 4 at 3Mbps. For these transmission rates, Tier 2 Controller controls the Tier2 Re-encoder to encode video data at the rate of the lowest-performingVirtual Transmitter in the tier, namely, at 3 Mbps to accommodateVirtual Transmitter 4.

As shown in FIG. 2A, the transmission rate of Virtual Transmitter 2 maydrop to 4 Mbps, e.g., as a result of reduced transmission capacity inthe link(s) (networks) interconnecting Virtual Transmitter 2 andReceiver 2. As this reduced bitrate is outside the range specified forTier 1, Virtual Transmitter 2 is moved to Tier 2 in manners disclosedherein. The reduced bitrate is within the range specified for Tier 2.

FIG. 2B is a graphical representation of a schematic diagram 200B afterthe movement of a virtual transmitter between tiers, according to someembodiments. Following this move, Tier 1 Controller controls the Tier 1Re-encoder to increase its encoding rate. In particular, the encodingrate is increased to 8 Mbps, corresponding to the rate of the newlowest-performing Virtual Transmitter in the tier, i.e., VirtualTransmitter 1.

In some embodiments, the virtual transmitter is able to initiate themovement of the virtual transmitter from one tier to another tier, forexample, where the virtual transmitter indicates that characteristics ofits transmission are changing (e.g., a higher bitrate is required, alower bitrate is required), and submits a control signal request to acontroller. The controller in this scenario may be configured tocoordinate the movement of the virtual transmitter to another tier.

Various steps may be undertaken to move a virtual transmitter from onetier to another. There may be some steps provided to facilitate thetransition such that the transition only results in change in the videoquality (e.g., there should be no dropped or duplicate frames).

The movement of a virtual transmitter from one tier to another may bebased on the following example steps to provide a seamless transition:

Tier signals to the Tier Controller of the desire to move the VirtualTransmitter (in some embodiments, the Tier Controller or the MPDController may be configured to monitor various aspects related to theTier and may initiate a move between tiers);

Tier Controller decides on the new Tier based on the bitrate (or othercriteria);

Tier Controller reads the presentation timestamp (PTS) of the next rawframe to be handled by the new tier—(e.g., PTSnew)

Tier Controller reads the PTS of the next frame expected by the VirtualTransmitter to be moved—(e.g., PTSnext)

There may be three cases depending on these values:

PTSnew==PTSnext—The Tier Controller requests a key frame from the newTier Re-encoder immediately, and the Virtual Transmitter is movedimmediately. The Virtual Transmitter starts to receive frames from thenew Tier, discarding all old frames until it is provided a frame stampedas PTSnew. For example, the re-encoder might have its own internalbuffering (e.g., an encoder could be configured for “lookahead”), andeven though a keyframe is requested immediately at PTSnew, and the nextframe entering that encoder is at PTSnew, the next frame that comes outof the encoder can be older (PTSnew minus the amount of “lookahead” theencoder is configured for). Accordingly, in some embodiments, all ofthese old frames would be discarded by the VTx until the encoded framestamped PTSnew is provided.

PTSnew<PTSnext—The Tier Controller requests a key frame from the newTier Re-encoder at PTSnext, and the Virtual Transmitter is movedimmediately. The Virtual Transmitter starts to receive frames from thenew Tier, discarding all old frames until it is provided a frame stampedas PTSnew.

PTSnew>PTSnext—The Tier Controller requests a key frame from the newTier Re-encoder at PTSnew, and the Virtual Transmitter enters an interimstate where it belongs to both tiers. It receives frames from bothTiers, but keeps them in a sorted queue. It continues to receive framesfrom the old Tier that are stamped between PTSnext and PTSnew. Meanwhileit also receives frames from the new Tier stamped PTSnew and beyond.When the old Tier finally catches up to PTSnew, the Virtual Transmitteris removed from the old Tier, and the queued frames are processed.

A Tier Re-encoder may be configured for periodic key frames instead ofkey frames on demand. In such a situation, the examples above wouldchange such that the Virtual Transmitter would wait until the nextperiodic key frame that is >=PTSnext before completing the Tier switch.

For example, when a virtual transmitter is unable to maintaintransmission at a minimum level of the tier it is in, it may beadaptively and seamlessly transferred to a lower tier, and be servicedby a different re-encoder using a different set of encoding parameters.Such movement may, in some embodiments, be used to increase transmissionefficiency, decrease encoding processing requirements and/or decreaseoverall costs associated with the transmission of signals.

In some embodiments, some or each network connection present in thevirtual transmitter executes a congestion control algorithm that, basedon feedback (e.g., real-time or near-real time), decides the bitrate atwhich it can reliably transmit to the destination. The bitratedetermined by this congestion control algorithm is provided back to thecontroller, which determines whether the VTx should be moved to adifferent grouping/tier (higher or lower).

The group that the virtual transmitter was in initially may beconfigured to then adapt by changing its encoding parameters to thevalue of the new lowest performing receiver. Other types of adaptationsmay be considered, and this example is provided merely for illustration.

In a similar manner, a virtual transmitter in a lower tier may indicatethat it would be able to meet the minimum transmission requirements of ahigher tier (through monitoring the attributes of the connection withthe receiver endpoint), and may be moved into a higher performing tier.

The higher tier may then be configured to adapt its encoding parametersto reflect the addition of the new virtual transmitter into its rank(presuming the new virtual transmitter was now the lowest performingvirtual in the higher tier). Other types of adaptations may beconsidered, and this example is provided merely for illustration.

Transfer between tiers (or removal/addition from stream entirely) may beperformed by sending key frame on demand or by sending one or more keyframes on a periodic interval, depending on tier and network conditions,and also by handing off timestamps, and by duplicating packets, or othermethods. For example, the system could continue sending framedifferences from the initial tier until a key frame from the new tier isreceived. More specifically, the examples above would change such thatthe virtual transmitter would wait until the first key frame>=PTSnew,rather than always expecting a key frame right at PTSnew.

During the interim period while the virtual transmitter is waiting for akey frame at PTSnew from the new Tier, it continues to consume framesfrom the old Tier and transmit them to the Receiver. If the frames fromthe old Tier cannot be reliably sent to the Receiver (e.g. because thebitrate is too high for the Receiver to support), the Tier switch willnot be seamless, and the Virtual Transmitter and Receiver may concealerrors as described in the '560 and '576 patents.

An example tier transfer is described in more detail below.

A problem that may arise in the context of transferring tiers may bethat the encoders in the tiers may not be synchronized (e.g., in termsof the PTS) of the media (e.g., video) frame they are currentlydisplaying and/or otherwise processing. This problem may happen as theencoders may be configured differently (e.g. different look aheadvalues), or simply because of operating system thread scheduling causingthe encoders to get slightly different amounts of CPU execution time.

The problem may arise in various contexts, and two sample cases aredescribed below. The first sample case considers a virtual transmitterthat wants to move from Tier 1 to Tier 2:

Case 1:

-   -   The Tier 1 encoder's current output frame is PTS 1000    -   The Tier 2 encoder's current output frame is PTS 1005    -   Virtual transmitter requests a key frame from Tier 2's encoder        in preparation for the switch    -   Assume the key frame comes out from Tier 2 at PTS 1010    -   So the virtual transmitter must continue to consume frames        1001-1009 from Tier 1 until it is provided and/or receives the        key frame from Tier 2 at 1010, where it can finally make the        switch.

Case 2:

-   -   The Tier 1 encoder's current output frame is PTS 1000    -   The Tier 2 encoder's current output frame is PTS 990    -   Virtual transmitter requests an key frame from Tier 2's encoder        in preparation for the switch, but requests it to occur for        PTS>=1000    -   Tier 2 waits until the next raw input frame is PTS 1001 before        asking the encoder to make it a key frame    -   Virtual transmitter switches to Tier 2, but discards all frames        until PTS 1001

The units in the above example are in those of the nominal video frameduration—(e.g., the PTS was incremented by 1 for each new video frame),but in practice the actual units may be arbitrary (e.g.,negotiated/agreed to by the involved parties).

The PTS may be used to synchronize media (e.g., video and/or audio)playback. For example, a video frame stamped with PTS 1000 must beplayed back at the same time as an audio frame stamped with PTS 1000.

If the new tier controller was on a different machine, handover wouldindeed be more complicated, for example, as the value of d(MPD-to-Rx)may be changing mid-stream. As part of the hand-over, the new target MPDand Rx may need to synchronize their timing. Then during the handoverthe Rx would have two values for d(MPD-to-Rx), and would need to knowwhen to switch over from the old value to the new one (essentially onthe new key frame).

FIG. 3A is an example schematic diagram 300A of a system scaled toinclude multiple MPD nodes 120 which are served by a proxy 170,according to some embodiments. The MPD nodes 120 and proxy 170 maycollectively be referred to as a proxy-scaled MPD block 310.

The MPD nodes 120 collectively function to distribute data received froma transmitter 102 to endpoints 104. Advantageously, the system of FIG.3A may allow more endpoints 104 to be serviced than the system of FIG.1.

Each of the MPD nodes 120 may be controlled by a master controller 160,using user input from a control portal 150. Master controller 160 isconfigured to control each of the MPD nodes 120, e.g., by distributingcontrol inputs from control portal 150 (e.g., inputs 125 a, 125 b, and125 c) to appropriate ones of the MPD nodes 120. In particular, thecontrol inputs may be distributed to MPD controllers 106 in the MPDnodes 120. Master controller 160 may also be configured to receivefeedback and status data from each of the MPD controllers 106.

Proxy 170 is configured to receive an encoded stream from transmitter102 and to repeat it to each of the MPD nodes 120, for decoding by adecoder 140 within each of the MPD nodes 120.

In this example, the system may be configured to provide MPD nodes 120on multiple computing resources (e.g., machines) in different locations(which may improve performance to a transmission by being near to eitherthe transmitter or receiver, or for other reasons), or in environmentswith network standards (e.g., one decoder may serve endpoints whichconnect to the cloud via satellite link, and which may have differentexpectations with respect to latency than for example, a group ofendpoints connected through a high-speed fibre line).

FIG. 3B is an example schematic diagram 300B of a system further scaledto provide multiple proxy-scaled MPD blocks 310. As depicted, the systemincludes an intermediate proxy 172 connected with a plurality ofproxy-scaled MPD blocks 310. Each of the proxy-scaled MPD blocks 310 isconfigured to service a subset of endpoints 114 a . . . n, e.g.,endpoints in a particular geographical region, or endpoints havingparticular transmission/encoding requirements.

The proxy-scaled MPD blocks 310 may be controlled by a master controller160, e.g., using input from control portal 150. In one example, mastercontroller 160 may control proxy-scaled MPD blocks 310 to redistributeendpoints amongst the blocks 310, and thereby balance the load betweenblocks 310. Master controller 160 may also cause blocks 310 to be spunup or spun down as required.

Advantageously, the system of FIG. 3B may allow even more endpoints 104to be serviced than the system of FIG. 3A.

Intermediate proxy 172 is configured to receive an encoded stream from atransmitter 102 and to repeat it to each of the proxy-scaled MPD blocks310. In particular, each repeated stream is provided to a proxy 170 in ablock 310, where it may be further distributed to multiple MPD nodes120.

Additional layers of proxies may be provided, e.g., to provide ahierarchy of proxies. For example, FIG. 3C illustrates a hierarchy ofproxies 300C including a master proxy 174, intermediate proxies 172, andproxies 170 (within proxy-scaled MPD blocks 310). Master proxy 174distributes data from a transmitter 102 to multiple intermediate proxies172. In turn, each intermediate proxy 172 distributes data to multipleproxies 170 (within proxy-scaled MPD blocks 310).

FIG. 4A is an example schematic diagram 400A of a system with multipletransmitters 102, according to some embodiments. In the depictedexample, each transmitter 102 may be serviced by a respective MPD node120. Data from each transmitter 102 may be decoded by a decoder 104 ineach of the respective MPD nodes 120.

The system may be configured to permit the selection and assignment oftransmitters 102 to endpoints 114 in manners disclosed above (e.g., byway of drag-and-drop). The system may also be configured to permit thepreview of streams from transmitters 102, including the preview ofstreams from multiple transmitters 102 at one endpoint 114.

The system may be configured to permit an endpoint 114 to switch fromone transmitter 102 to another transmitter 102. For example, such aswitch may be performed in response to receiving a user request, whichmay be issued by way of the multi-viewer system noted above. Therequested switch may be provided by re-assigning the endpoint 114 to anew virtual transmitter 112, e.g., a transmitter 112 associated with thenewly requested transmitter 102.

Conveniently, there may already be a re-encoder 110 receiving andre-encoding data for the newly requested transmitter 102 (e.g., fortransmission to one or more other endpoints 114) in a suitable form(e.g., suitable bitrate and encoding format). In such cases, data fromthe new transmitter 102 (including data received at an MPD node 120before the switch is requested) may be transmitted to the endpoint 114,thereby allowing the switch to be effected in a low latency manner.

FIG. 4B is an example schematic diagram 400B of a system with multiplereplicated virtual transmitter blocks 130, according to someembodiments.

In some embodiments, there may be multiple virtual transmitter blocks130 associated with a particular tier. These virtual transmitter blocks130 may be provisioned or de-provisioned (e.g., in the context of acloud computing implementation, “spun up” or “spun down”) by a tiercontroller 108 and each of the virtual transmitter blocks 130 mayinclude one or more virtual transmitters 112, each virtual transmitter112 being configured to communicate data to a corresponding receiverendpoint 114.

In the context of the example depicted in FIG. 4B, tier controller 108 amay be associated with a replicator 402 a and a feedback aggregator 404a.

The re-encoded data output of the tier controller 108 a and the tierre-encoder 110 a may be replicated by replicator 402 a, which thenprovides the replicated re-encoded data to one or more virtualtransmitter blocks 130 a _(i) . . . 130 a _(n) for transmission to theirrespective receiver endpoints. In some embodiments, the replicator 402 aalso transmits various transmission parameters, metadata and/or controlsignals that may otherwise be provided by tier controller 108 a and/ortier re-encoder 110 a. Although replicator 402 a may be shown in FIG. 4Bonly for the tier associated with tier controller 108 a, there may beother replicators 402 provided for other tiers associated with othertier controllers (e.g., 108 b . . . 108 n).

A potential benefit of using the replicator 402 a to communicate there-encoded output to the virtual transmitter blocks 130 a _(i) . . . 130a _(n) is that there may be a reduced and/or eliminated need for thetier re-encoder 110 a to transmit information directly to a large numberof virtual transmitter blocks 130 a _(i) . . . 130 a _(n). There mayalso be a reduced and/or eliminated need for each virtual transmitter112 to be “spun up” or “spun down” individually.

For example, in the context of an implementation where there is asignificant number of virtual transmitters being serviced by a singletier re-encoder 110 a without a replicator, the performance of the tierre-encoder 110 a may be impacted by the need to transmit information toa large number of virtual transmitters in addition to the encodingfunctions performed by tier re-encoder 110 a. Accordingly, a potentialbenefit of using the replicator 402 a may be to improve the scalabilityof a MPD node 120, enabling the MPD node to service a larger number ofreceiver endpoints 114.

The feedback aggregator 404 a may be provided to receive variousfeedback information (e.g., signal quality, noise, packet loss, latency)from the virtual transmitter blocks 130 a _(i) . . . 130 a _(n),aggregate the received feedback information and/or provide an aggregateset of feedback information to the tier controller 108 a. The feedbackaggregator 404 a may monitor utilization of the virtual transmitters 112and/or virtual transmitter blocks 130 a _(i) . . . 130 a _(n) (e.g.,which are coupled with various receiver endpoints 114). Althoughfeedback aggregator 404 a may be shown in FIG. 4B only for the tierassociated with tier controller 108 a, there may be other feedbackaggregators 404 provided for other tiers associated with other tiercontrollers (e.g., 108 b . . . 108 n).

The tier controller 108 a may utilize the feedback information inmanaging and/or controlling the operation of the replicator 402 a, thefeedback aggregator 404 a, the number of virtual transmitter blocks 130a _(i) . . . 130 a _(n), and/or the membership of the virtualtransmitters in the virtual transmitter blocks 130 a _(i) . . . 130 a_(n).

The tier controller 108 may be configured to control various aspects ofthe operation of the replicator 402, the virtual transmitter blocks 130a _(i) . . . 130 a _(n), and/or the virtual transmitters 112. Forexample, the tier controller 108 may determine the number of virtualtransmitter blocks required to service the virtual transmitters, forexample, dynamically “spinning up” and/or “spinning down” resources(e.g., virtual transmitter blocks), changing the membership of virtualtransmitters from one virtual transmitter block to another (e.g.,changing the distribution of virtual transmitters), performing loadbalancing across various virtual transmitter blocks (e.g., re-allocatingvirtual transmitters between virtual transmitter blocks to promote aneven distribution of virtual transmitters), etc.

The membership of virtual transmitters in virtual transmitter blocks maybe based on various factors, such as geography (e.g., grouping togetherall the virtual transmitters for receiver endpoints on the East coast ofthe United States in one or more virtual transmitter blocks),transmission characteristics (e.g., latency, packet loss), etc.

In some embodiments, the transfer of virtual transmitters betweenphysical machines may be performed during a live stream for the purposesof load distribution or failover. For example, the system may determinethat there is a large number of endpoints and/or virtual transmittersassociated with a particular group (e.g., or tier), which may indicatethat the encoder and/or transmission links associated with that groupmay be under a relatively larger load.

In some embodiments, where one or more encoders fail and/or othercomponents fail and/or have performance issues, the system may beconfigured to invoke a transfer of endpoints from one or more groups toother one or more groups.

In one example, the system may contain stations which may each serve asboth a transmitter 102 and a receiver endpoint 114, as a transmitter 102only, or as a receiver endpoint 114 only. In one embodiment, this systemis configured to allow a group of stations to transfer data, includingbut not limited to live video data, from station to station by way ofthe cloud, potentially reducing and/or eliminating the need for costlypoint to point video transmission systems, and allowing transfer throughvarious networks, such as the Internet.

In some embodiments, the system may be implemented in part, or in full,by a set of distributed computing devices connected through acommunications network. An example of such a set of distributedcomputing devices would be what is typically known as a ‘cloudcomputing’ implementation. In such a network, a plurality of connecteddevices operate together to provide services through the use of theirshared resources.

A cloud-based implementation for distributing information may provideone or more advantages including: openness, flexibility, andextendibility; manageable centrally; reliability; scalability; on-demandprovisioning; being optimized for computing resources; being optimizedfor latency; among others. While embodiments and implementations may bediscussed in particular non-limiting examples with respect to use of thecloud to implement aspects of the system platform, a local server, asingle remote server, a software as a service platform, or any othercomputing device may be used instead of the cloud. In some embodiments,where the encoders are provided as cloud-based resources, new encodersmay be provisioned where necessary to establish new tiers in a dynamicmanner when required. Conversely, encoders that are no longer necessarymay also be de-provisioned and returned into cloud resources. In someembodiments, encoders are provided in the form of a physical encoderfarm, from which encoder resources are provisioned from and/orde-provisioned to, depending on the need of a system. For example, acontroller may determine that to increase efficiency, a new tier mayneed to be established (e.g., a current tier spans too large a range ofbitrates and is thus sub-optimally encoding), and a new encoder may beprovisioned from the encoder farm.

FIG. 7 is an example workflow illustrating steps that may be taken tomove a virtual transmitter from one tier to another, according to someembodiments. As illustrated in workflow 700, various steps areillustrated and there may be more, different, alternate, or less steps,and the steps may be taken in various permutations, combinations, and/orsub-combinations. For example, the steps may be taken out of the orderdepicted, with various steps substituted and/or otherwise omitted.

At 702, the controller is configured to monitor transmissioncharacteristics of the plurality of virtual transmitters and at 704, toadjust membership of the virtual transmitters in the plurality of groups(e.g., ranked tiers) based on the monitored transmissioncharacteristics. In some embodiments, transmission characteristics mayinclude bitrates, latency, packet loss, QoS, communication link quality,signal-to-noise ratio, among others.

The controller is configured to dynamically adjust the membership of thevirtual transmitters in the plurality of groups, for example, based onthe monitored transmission characteristics. A potential benefit may bethe ability to adaptively adjust to changing channel conditions and/ornetwork conditions. For example, a virtual transmitter may be determinedto have superior transmission characteristics relative to its peers inits tier and thus is a candidate for promotion to a better encodingtier. Conversely, inferior transmission characteristics may lead to ademotion to a lower tier. Accordingly, the adjustment of membershiphelps ensure that virtual transmitters are grouped into groups that arefit for purpose (e.g., matched based on the transmissioncharacteristics). In some embodiments, a weighted combination of thetransmission characteristics is utilized (e.g., weighted indicative ofthe relative importance of the contribution of each of the transmissioncharacteristics to the quality of transmission and/or channel capacity).

At 706, upon a determination that a group membership adjustmentcondition has been triggered (e.g., latency has grown above a particularvalue, packet loss is greater than a predefined threshold, latency hasbeen low for a predefined period of time), the controller determines anew group for a target virtual transmitter that is currently a member ofa current group, the new group based on the monitored transmissioncharacteristics.

At 708, the controller tracks a current frame number being processed bythe current group and checks to see if it matches a new frame numberbeing processed by the new group; generate and at 710 transmits acontrol signal to an encoder corresponding to the new group requestingprovisioning of the target virtual transmitter as a member of the newgroup.

At 712, the controller requests a key frame from the encodercorresponding to the new group; and upon a determination that thecurrent frame number does not match the new frame number at 714,generate or transmit one or more control signals to synchronize thetarget virtual transmitter to the encoder corresponding to the newgroup.

FIG. 8 is an example workflow illustrating steps that may be taken forsynchronizing a move of the virtual transmitter from one tier toanother, according to some embodiments. As illustrated in workflow 800,various steps are illustrated and there may be more, different,alternate, or less steps, and the steps may be taken in variouspermutations, combinations, and/or sub-combinations. For example, thesteps may be taken out of the order depicted, with various stepssubstituted and/or otherwise omitted.

Upon a determination that the current frame number does not match thenew frame number at 802, the controller checks if the current framenumber is greater or less than the new frame number at 804. One of thechallenges with dynamically transitioning virtual transmitters betweentiers is that there is a risk of inadvertently causing “skipping” as theframes being transferred by the encoders for each tier may not besynchronized. This may result in a suboptimal experience as thetransition is no longer seamless, and a potential loss of information.As described below, some aspects include steps for synchronization to betaken as part of the transition process.

To synchronize the virtual transmitter when the current frame number isgreater than the new frame number, the at least one controller isconfigured at 806B to transmit a control signal to an encodercorresponding to the current group terminating membership of the targetvirtual transmitter and at 808B transmit a control signal to the virtualtransmitter to discard frames provided by the encoder corresponding tothe new group until frames provided by the encoder corresponding to thenew group reach the current frame number.

To synchronize the virtual transmitter when the current frame number isless than the new frame number, the at least one controller isconfigured to at 806A maintain membership of the target virtualtransmitter in both the current group and the new group and at 808Astore the frames provided by the encoder corresponding to the new groupin a sorted queue until the frames provided by the encoder correspondingto current group match the earliest frame provided by the encodercorresponding to the new group.

At this time, the controller at 810A is configured to transmit a controlsignal to the encoder corresponding to the current group terminatingmembership of the target virtual transmitter and at 812A to transmit acontrol signal to the virtual transmitter to process the frames storedin the sorted queue.

Control signals may be in the form of a notification sent through anapplication programming interface, a function call, machine-levelinstruction sets, object code, etc. In some embodiments, an interface isupdated to indicate the transition of tiers to either an end user (e.g.,associated with the virtual transmitter) or to an operator of thecontroller.

The embodiments of the devices, systems and methods described herein maybe implemented in a combination of both hardware and software. Theseembodiments may be implemented on programmable computers, each computerincluding at least one processor, a data storage system (includingvolatile memory or non-volatile memory or other data storage elements ora combination thereof), and at least one communication interface.

In some embodiments, the communication interface may be a networkcommunication interface. In embodiments in which elements may becombined, the communication interface may be a software communicationinterface, such as those for inter-process communication. In still otherembodiments, there may be a combination of communication interfacesimplemented as hardware, software, and combination thereof.

Throughout the foregoing discussion, numerous references will be maderegarding servers, services, interfaces, portals, platforms, or othersystems formed from computing devices. It should be appreciated that theuse of such terms is deemed to represent one or more computing deviceshaving at least one processor configured to execute softwareinstructions stored on a computer readable tangible, non-transitorymedium. For example, a server can include one or more computersoperating as a web server, database server, or other type of computerserver in a manner to fulfill described roles, responsibilities, orfunctions.

One should appreciate that the systems and methods described herein mayprovide for more efficient encoding, better utilization of communicationlinks, more responsive adaptations to changing communications demandsand/or network conditions.

The foregoing discussion provides many example embodiments. Althougheach embodiment represents a single combination of inventive elements,other examples may include all possible combinations of the disclosedelements. Thus if one embodiment comprises elements A, B, and C, and asecond embodiment comprises elements B and D, other remainingcombinations of A, B, C, or D, may also be used.

The term “connected” or “coupled to” may include both direct coupling(in which two elements that are coupled to each other contact eachother) and indirect coupling (in which at least one additional elementis located between the two elements).

The technical solution of embodiments may be in the form of a softwareproduct. The software product may be stored in a non-volatile ornon-transitory storage medium, which can be a compact disk read-onlymemory (CD-ROM), a USB flash disk, or a removable hard disk. Thesoftware product includes a number of instructions that enable acomputer device (personal computer, server, or network device) toexecute the methods provided by the embodiments.

The embodiments described herein are implemented by physical computerhardware, including computing devices, servers, receivers, transmitters,processors, memory, displays, and networks. The embodiments describedherein provide useful physical machines and particularly configuredcomputer hardware arrangements. The embodiments described herein aredirected to electronic machines and methods implemented by electronicmachines adapted for processing and transforming electromagnetic signalswhich represent various types of information. The embodiments describedherein pervasively and integrally relate to machines, and their uses;and the embodiments described herein have no meaning or practicalapplicability outside their use with computer hardware, machines, andvarious hardware components. Substituting the physical hardwareparticularly configured to implement various acts for non-physicalhardware, using mental steps for example, may substantially affect theway the embodiments work. Such computer hardware limitations are clearlyessential elements of the embodiments described herein, and they cannotbe omitted or substituted for mental means without having a materialeffect on the operation and structure of the embodiments describedherein. The computer hardware is essential to implement the variousembodiments described herein and is not merely used to perform stepsexpeditiously and in an efficient manner.

For simplicity only one computing device 600 is shown in FIG. 6 but thesystem may include more computing devices 600 operable by users toaccess remote network resources 600 and exchange data. The computingdevices 600 may be the same or different types of devices. The computingdevice 600 at least one processor, a data storage device (includingvolatile memory or non-volatile memory or other data storage elements ora combination thereof), and at least one communication interface. Thecomputing device components may be connected in various ways includingdirectly coupled, indirectly coupled via a network, and distributed overa wide geographic area and connected via a network (which may bereferred to as “cloud computing”).

For example, and without limitation, the computing device may be aserver, network appliance, set-top box, embedded device, computerexpansion module, personal computer, laptop, personal data assistant,cellular telephone, smartphone device, UMPC tablets, video displayterminal, gaming console, electronic reading device, and wirelesshypermedia device or various computing devices capable of beingconfigured to carry out the methods described herein.

FIG. 6 is a schematic diagram of a computing device 600, exemplary of anembodiment. As depicted, computing device 600 includes at least oneprocessor 60002, memory 60004, at least one I/O interface 60006, and atleast one network interface 60008.

Each processor 60002 may be, for example, various types ofmicroprocessor or microcontroller, a digital signal processing (DSP)processor, an integrated circuit, a field programmable gate array(FPGA), a reconfigurable processor, a programmable read-only memory(PROM), or any combination thereof.

Memory 60004 may include a suitable combination of any type of computermemory that is located either internally or externally such as, forexample, random-access memory (RAM), read-only memory (ROM), compactdisc read-only memory (CDROM), electro-optical memory, magneto-opticalmemory, erasable programmable read-only memory (EPROM), andelectrically-erasable programmable read-only memory (EEPROM),Ferroelectric RAM (FRAM) or the like.

Each I/O interface 60006 enables computing device 600 to interconnectwith one or more input devices, such as a keyboard, mouse, camera, touchscreen and a microphone, or with one or more output devices such as adisplay screen and a speaker.

Each network interface 60008 enables computing device 600 to communicatewith other components, to exchange data with other components, to accessand connect to network resources, to serve applications, and performother computing applications by connecting to a network (or multiplenetworks) capable of carrying data including the Internet, Ethernet,plain old telephone service (POTS) line, public switch telephone network(PSTN), integrated services digital network (ISDN), digital subscriberline (DSL), coaxial cable, fiber optics, satellite, mobile, wireless(e.g., W-Fi, WiMAX), SS7 signaling network, fixed line, local areanetwork, wide area network, and others, including any combination ofthese.

Computing device 600 may be operable to register and authenticate users(using a login, unique identifier, and password for example) prior toproviding access to applications, a local network, network resources,other networks and network security devices. Computing devices 600 mayserve one user or multiple users.

Although the embodiments have been described in detail, it should beunderstood that various changes, substitutions and alterations can bemade herein.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized. Accordingly, the embodiments areintended to include within their scope such processes, machines,manufacture, compositions of matter, means, methods, or steps.

As can be understood, the examples described above and illustrated areintended to be exemplary only.

What is claimed is:
 1. A system for transmission of data streams to aplurality of endpoints, the system comprising: a plurality of encoders,each encoder configured to encode a data stream according to at leastone encoding parameter; a plurality of virtual transmitters organizedinto a plurality of groups based on at least one transmissioncharacteristic; each group of virtual transmitters configured to receiveencoded data from an associated one of the encoders; each virtualtransmitter of the plurality of virtual transmitters configured totransmit the encoded data to an associated one of the plurality ofendpoints; and at least one controller configured to monitortransmission characteristics of the plurality of virtual transmittersand to adjust membership of the virtual transmitters in the plurality ofgroups based on the monitored transmission characteristics.
 2. Thesystem of claim 1, wherein at least some of the groups correspond toranked tiers, ranked according to the at least one transmissioncharacteristic.
 3. The system of claim 2, wherein the at least onecontroller is configured to adjust the membership of the virtualtransmitters in the plurality of groups, the at least one controllerbeing configured to: upon a determination that a group membershipadjustment condition has been triggered, determine a new group for atarget virtual transmitter that is currently a member of a currentgroup, the new group based on the monitored transmissioncharacteristics; determine whether a current frame number beingprocessed by the current group matches a new frame number beingprocessed by the new group; generate and transmit a control signal to anencoder corresponding to the new group requesting provisioning of thetarget virtual transmitter as a member of the new group; request a keyframe from the encoder corresponding to the new group; and upon adetermination that the current frame number does not match the new framenumber, generate or transmit one or more control signals to synchronizethe target virtual transmitter to the encoder corresponding to the newgroup.
 4. The system of claim 3, wherein to synchronize the virtualtransmitter when the current frame number is greater than the new framenumber, the at least one controller is configured to: transmit a controlsignal to an encoder corresponding to the current group terminatingmembership of the target virtual transmitter and transmit a controlsignal to the virtual transmitter to discard frames provided by theencoder corresponding to the new group until frames provided by theencoder corresponding to the new group reach the current frame number.5. The system of claim 3, wherein to synchronize the virtual transmitterwhen the current frame number is less than the new frame number, the atleast one controller is configured to: maintain membership of the targetvirtual transmitter in both the current group and the new group andstore the frames provided by the encoder corresponding to the new groupin a sorted queue until the frames provided by the encoder correspondingto current group match the earliest frame provided by the encodercorresponding to the new group, upon which the at least one controlleris configured to transmit a control signal to the encoder correspondingto the current group terminating membership of the target virtualtransmitter and to transmit a control signal to the virtual transmitterto process the frames stored in the sorted queue.
 6. The system of claim1, wherein each encoder of the plurality of encoders is configured toencode the data stream according to a lowest transmission characteristicamong the plurality of virtual transmitters that are members of thegroup corresponding to the encoder.
 7. The system of claim 1, whereinthe at least one controller is configured to monitor load conditions,each load condition associated with an encoder of the plurality ofencoders, and upon detecting load conditions greater than apredetermined load condition value, to provision a new encoder and acorresponding new group, and to adjust membership of the virtualtransmitters in the plurality of groups such that the virtualtransmitters are distributed substantially evenly amongst the pluralityof groups.
 8. The system of claim 1, further comprising a decoderconfigured to decode data received from a data source, and to providethe decoded data to each of the plurality of encoders.
 9. The system ofclaim 1, further comprising a plurality of decoders, each associatedwith at least one of plurality of encoders, each of the decodersconfigured to decode data received from a data source, and to providethe decoded data to the associated encoders.
 10. The system of claim 1,wherein the at least one transmission characteristic comprises at leastone of: a bitrate, a latency, an encoding error rate relative toindividual encoding, a structural similarity metric, a picturesimilarity index, and a packet loss rate.
 11. A computer-implementedmethod for transmission of data streams to a plurality of endpoints, themethod comprising: monitoring, by at least one controller, transmissioncharacteristics of a plurality of virtual transmitters; and adjustingmembership of the virtual transmitters in a plurality of groups based onthe monitored transmission characteristics; wherein a plurality ofencoders are each configured to encode a data stream according to atleast one encoding parameter, and the plurality of virtual transmittersare organized into the plurality of groups based on at least onemonitored transmission characteristic; wherein each group of virtualtransmitters is configured to receive encoded data from an associatedone of the encoders; and each virtual transmitter of the plurality ofvirtual transmitters is configured to transmit the encoded data to anassociated one of the plurality of endpoints.
 12. The method of claim11, wherein at least some of the groups correspond to ranked tiers,ranked according to the at least one transmission characteristic. 13.The method of claim 12, wherein adjusting the membership of the virtualtransmitters in the plurality of groups, further includes: upon adetermination that a group membership adjustment condition has beentriggered, determining a new group for a target virtual transmitter thatis currently a member of a current group, the new group based on themonitored transmission characteristics; determining whether a currentframe number being processed by the current group matches a new framenumber being processed by the new group; generating and transmitting acontrol signal to an encoder corresponding to the new group requestingprovisioning of the target virtual transmitter as a member of the newgroup; requesting a key frame from the encoder corresponding to the newgroup; and upon a determination that the current frame number does notmatch the new frame number, generating or transmitting one or morecontrol signals to synchronize the target virtual transmitter to theencoder corresponding to the new group.
 14. The method of claim 13,wherein to synchronize the virtual transmitter when the current framenumber is greater than the new frame number, the method comprises:transmitting a control signal to an encoder corresponding to the currentgroup terminating membership of the target virtual transmitter andtransmitting a control signal to the virtual transmitter to discardframes provided by the encoder corresponding to the new group untilframes provided by the encoder corresponding to the new group reach thecurrent frame number.
 15. The method of claim 13, wherein to synchronizethe virtual transmitter when the current frame number is less than thenew frame number, the method comprises: maintaining membership of thetarget virtual transmitter in both the current group and the new group;storing the frames provided by the encoder corresponding to the newgroup in a sorted queue until the frames provided by the encodercorresponding to current group match the earliest frame provided by theencoder corresponding to the new group; when the frames provided by theencoder corresponding to current group match the earliest frame providedby the encoder corresponding to the new group, transmitting a controlsignal to the encoder corresponding to the current group terminatingmembership of the target virtual transmitter; and transmitting a controlsignal to the virtual transmitter to process the frames stored in thesorted queue.
 16. The method of claim 11, wherein each encoder of theplurality of encoders is configured to encode the data stream accordingto a lowest transmission characteristic among the plurality of virtualtransmitters that are members of the group corresponding to the encoder.17. The method of group 11, further comprising: monitoring loadconditions, each load condition associated with an encoder of theplurality of encoders; and upon detecting load conditions greater than apredetermined load condition value, provisioning a new encoder and acorresponding new group, and adjusting membership of the virtualtransmitters in the plurality of groups such that the virtualtransmitters are distributed substantially evenly amongst the pluralityof groups.
 18. The method of claim 11, further comprising a decoderconfigured to decode data received from a data source, and to providethe decoded data to each of the plurality of encoders.
 19. The method ofclaim 11, further comprising a plurality of decoders, each associatedwith at least one of plurality of encoders, each of the decodersconfigured to decode data received from a data source, and to providethe decoded data to the associated encoders.
 20. The method of claim 11,wherein the at least one transmission characteristic comprises at leastone of: a bitrate, a latency, an encoding error rate relative toindividual encoding, a structural similarity metric, a picturesimilarity index, and a packet loss rate.